Size-Specific Dose Estimate for Chest of Adult Patients in 128- Slice Computed Tomography at Rajavithi Hospital

Aims: To determine the patient radiation dose using Size-Specific Dose Estimates (SSDEs) for chest CT in adult patients performed with 128-slice CT technology. Study Design: A descriptive cross-sectional study was conducted as a retrospective analysis. Place and Duration of Study: Department of Radiology, Rajavithi Hospital, between April 1 and September 30, 2021. Methods: We included 500 patients (209 males, 291 females). All patients underwent chest contrast enhancement with a venous phase protocol. The patient radiation dose in terms of SSDE was calculated based on AP+Lat dimensions, effective diameter, and water-equivalent diameter. SSDEs was measured from the middle slice of the scan range. The conversion factors following body size and composition were applied according to the AAPM Reports No. 204 and 220 recommendations. Additionally, the study assessed the effective dose and dose-length product (DLP). Key parameters, including DLP, CTDIvol, effective dose, and SSDEs at the 75th percentile, were evaluated to determine radiation dose levels. These values were then compared with established national and international diagnostic reference levels. Results: The study found that the mean DLP was 301.74 mGy·cm, CTDIvol was 8.38 mGy, effective dose was 4.22 mSv, SSDE (AP+Lat) was 11.80 mGy, SSDE (Effective Diameter) was 11.86 mGy, and SSDE (Dw) was 12.91 mGy. When compared with reference radiation dose values from Thailand and international standards, the DLP, CTDIvol, and effective dose values were found to be lower than both Thai and international reference values. In contrast, the SSDE (AP+Lat) was also lower than previously reported findings. Additionally, the study found no available comparative data for SSDE (Effective Diameter) and SSDE (Dw). Conclusion: The comparison of radiation dose values using SSDE across the three methods revealed highly consistent results. The SSDE values obtained from this study can serve as reference levels for the radiation doses received by patients undergoing CT scans at the Radiology Department of Rajavithi Hospital. These values are instrumental in assessing the appropriateness of radiation doses applied during CT imaging and can serve as benchmarks for future dose optimization efforts. Furthermore, this study highlights the significance of evaluating radiation doses in diagnostic imaging, providing valuable baseline data that enhances our understanding of the radiation risks associated with various types of examinations. Further research is warranted to investigate radiation exposure in computed tomography for other body regions.